Fluid actuated impact tool



July 31, 1956 Filed July 23, 1954 R. BASSINGER FLUID ACTUATED IMPACT TOOL 5 Sheets-Sheet 1 R0 JJ Bass/179's)" INVENTOR.

BY I

ATT VPNEKS July 31, 1956 BASSINGER 2,756,966

FLUID ACTUATED. IMPACT TOOL Filedduly 25, 1954 5 Sheets-Sheet 2 R066 Bosslflyer INVENTOR.

A TTORNEKS July 31, 1956 Filed July 23, 1954 i N\ k R. BASSINGER FLUID ACTUATED IMPACT TOOL 5 Sheets-Sheet 3 &

IN VEN TOR.

Ross Bass/179a" ,4 TTORNE Y6 July 31, 1956 R. BASSINGER FLUID ACTUATED IMPACT TOOL Filed July 23, 1954 5 Sheets-Sheet 4 INVENTOR. Ross BcIss/nger BY @ILWK" A TTORNEYS July 31, 1956 BASSWGER 2,756,966

FLUID ACTUATED IMPACT TOOL Filed July 25, 1954 5 Sheets-Sheet 5 INVENTOR. H055 Basmnyer ATTORNEYS United States Patent Oli'tice 2,756,966 Patented July 31, 1956 FLUID A'CTUATED IMPACT TOOL Ross Bassinger, San Antonio, Tex.

Application July 23, 1954, Serial No. 446,042

24 Claims. (Cl. 255-44) This invention relates to a fluid actuated impact tool suitable for use as in earth drilling. In one of its aspects, it relates to a percussion drilling tool wherein means are provided for periodically lifting a bit' attached to the tool.

The general object of the invention is to provide an improved impact tool whereby the drilling of bore holes in earth formations will be facilitated and the cost thereof reduced.

In the percussion drilling tools heretofore used in the drilling of wells, a spring biased reciprocating hammer has been employed to deliver percussive energy through a drilling bit to the formation being penetrated. In such tools, the hammer is driven in one direction by fluid power and in the other direction by a spring. Obviously energy is required to compress the spring and, accordingly, the amount of percussive energy deliverable to the formation being drilled is limited by this factor. However, this has not heretofore been a serious disadvantage due to the fact that such drilling tools have been largely used with rotary bits which, due to their structure, are unable to withstand any large impact stresses impressed by the hammer so that the limited energy delivered by the hammer was satisfactory and prevented broken bits. Now, however, with recent developments in bits for percussive drilling, particularly in solid head bits with tungsten carbide inserts, there has arisen a demand for a much greater amount of percussive energy deliverable by a percussion tool to a formation. However, when using solid head bits, it has been found that they tend to become wedged in the formation, particularly in hard formations, so that rotational indexing of the bit for a new bite has become a serious problem. One reason for this is that in the percussion tools heretofore used, it has been found necessary that the bit or bit carrier be splined to the tubular drill string to permit limited longitudinal movement therebetween, and that the bit be preloaded. Such preloading tends to prevent indexing of the bit so that it becomes wedged in a cut on the bottom of the hole, to be driven deeper and deeper thereinto by succeeding blows.

Recent percussive drilling develouments have indicated that in many instances it is desirable to decrease the amplitude of the percussive blow while increasing the frequency thereof. This would not only favor the use of the more fragile rotary bit but also, in' certain instances, may increase the footage drilled through particular types of formations. However, to decrease the amplitude of the blow, it will be necessary to decrease the weight of the hammer and increase the frequency of the blows in order to maintainthe total energy input to the formation. The lighter hammer, reciprocating at a high rate, will deliver as much or more energy as a heavier hammer reciprocating at a slower rate due to the higher velocity of the lighter hammer upon impingement with the striking face of the anvil.

This invention has for one of its objects the provision of a percussive drilling tool which, while adapted to be used in conjunction with a rotary bit and to deliver high pact tool powered by a unidirectional flow of fluid wherein the power output has as its only substantial limitation the capacity of the fluid pumps supplying such fluid to the tool.

Another object of this invention is to provide a percussion tool powered by a unidirectional flow of fluid in such a manner that the fluid actuates a hammer to drive it alternately in opposite directions.

Another object of this invention is to provide a percussion tool adapted to deliver percussive blows to an anvil or to a bit, the hammer being reciprocated by two fluid motors powered by unidirectional flow of fluid'so that the hammer is, in effect, double acting and is driven by the fluid in both its power stroke and its return stroke.

Another object of this invention is to provide a percussion tool wherein a reciprocal hammer is moved in one direction by a unidirectional fluid moving generally in an opposite direction from the hammer, and wherein the fluid subsequently acts to accelerate movement of the hammer in a direction the same as that of the movement, to deliver a percussive blow to an anvil, the direction of the fluid flow being generally unchanged throughout the cycle.

Another object of this invention is to provide a percussion tool having a hammer adapted to be driven in both its power and return strokes between an anvil and a fluid supply conduit by fluid motors powered by a unidirectional flow of fluid and which is also adapted to be adjusted from a remote position so that it is driven only during one of such strokes.

Another object of this invention is to provide a percussion drilling tool wherein a drilling bit is lifted from the bottom of a bore hole between percussive blows delivered thereto in order that the bit can be indexed.

Another object of this invention is to provide a percussion tool wherein the return stroke of the hammer is hydraulically halted by a counterflowing fluid after which the fluid accelerates the hammer in an opposite direction in a power stroke.

Another object of this invention is to provide a percussion tool wherein valve means are provided to impress the force of a counterflowing fluid on a hammer to stop the same, the valve means being so constructed and arranged as to permit overtravel by the hammer from the position at which said force is brought to bear thereon.

Another object of this invention is to provide in such type of tool means whereby the force exerted on the hammer to return it from its power stroke can be controlled from the surface while the drilling operation is proceeding.

Another object of this invention is to provide a percussion tool wherein the frequency and length of the hammer stroke can be regulated from a remote position.

Another object of this invention is to provide a percussive drilling tool adapted to be attached to a bit and so constructed and arranged that the bit can be hopped from the bottom of the bore hole to permit indexing of the same or it can be continuously maintained on the bottom.

Another object is to provide a percussive drilling tool constructed so that it can be run into a bore hole containing a liquid with the latter flowing into and through tion will be apparent to one skilled in the art upon a consideration of the written specification, the appended claims and the attached drawings, wherein:

Figs. 1 to 6, inclusive, illustrate schematically the operation of the impact tool of this invention;

Figs. 7A, 7B, 7C and 7D illustrate the mechanical details of one embodiment of this invention, it being understood that these four figures are continuations of one another from top to bottom inthe order enumerated;

Figs. 8, 9, l0, ll and 12 are cross-sectional views taken on the lines 8-3 to 12-12,, inclusive, of Figs. 7A to 7D; and

Fig. 13 illustrates another form of valve means adapted to be substituted for those shown in Figs. 7A to 7D.

Like characters of reference are used throughout the several views to designate like parts.

Referring to the drawings, there is shown a reciprocal hammer designated generally by the numeral 10, connected between a fluid supply conduit 11 and an anvil 12 by suitable inter-engaging slide and guide parts providing for limited longitudinal movement of said hammer and conduit relative to each other and of said hammer and anvil relative to each other so that the hammer can deliver percussive blows to the anvil. The hammer is comprised of a plurality of sections detachably joined together as by threaded connections to permit ready assembly of the tool. These sections include an elongate, heavy walled section 13, a top section 13a, a sub 1321,

a lower valve housing section 130 and an impact section- 13d. Section 13 can have walls of such thickness as to provide the necessary weight for the hammer and, if desired, a plurality of interchangeable sections 13 of different wall thicknesses and lengths can be provided to permit varying the weight of the hammer.

The upper end of hammer section 13a can have a shoulder 14 formed by a reduced diameter portion 15, the latter slidably telescoping within the lower end portion of fluid supply conduit 11 for a purpose described below.

Fluid supply conduit 11 can be composed of aplurality of lengths 36a, 16b and lids joined together by threaded joints and adapted to receive a drill tubing or collar 17 at one end thereof. Section 16a is provided as a retainer for a key 19 and as a replaceable wear member.

Since fluid supply conduit 11 is maintained relatively fixed in elevation with respect to its operating environment such as a bore hole, during any one phase of the operation of the apparatus of this invention and since hammer reciprocates with respect thereto, there is a slidable connection between the hammer and conduit comprising interengaging slide and guide parts providing for limited longitudinal movement of the conduit and hammer relative to each other. This connection is so constructed and arranged as to permit reciprocation of the hammer with respect to the fluid supply conduit but to prevent relative rotation therebetween and also to permit the hammer to depend from the supply conduit in extended position with respect to the conduit while the tool is being positioned for operation. Such a connection can be telescopic and can comprise a keyed joint with a plurality of grooves or keyways l8 slidably engaging keys 19, the latter being firmly held in position between a bottom shoulder formed by the end of length 1615 and an inturned shoulder 24) on length 16a of the fluid supply conduit. In this manner, the hammer is free to reciprocate throughout the length of keyways 18 and, when the tool is being lowered into a bore hole, for example, the hammer will hang from the fluid supply conduit with the upper end of keyways 18 in abutment with the upper end of keys 19 and with shoulder 14 of the hammer parted or removed from the lower end of the fluid supply conduit length 16a.

Forming an upper extension or continuation of reduced diameter portion l5, and hence being a part of the hamn1er, is a fluid inlet conduit. This conduit can comprise a wash pipe 21 received in a counterbore 22 of portion so that a shoulder 23 on the wash pipe engages a corresponding shoulder in the counterbore and is held in place by a lock nut 24 threaded into portion 15. Lock nut 24 has locking lugs 25 adapted to be bent down over the upper end of portion 15 tolock the nut in position. A suitable sealing means, such as O-ring 26, can be provided at one end of the threaded connection between lock nut 2.4 and portion 15.

The end of wash pipe 21 most removed from portion 15 of the hammer carries a valve-element-supporting, spider-type sleeve 28, the latter having a free running fit over the upper end of the wash pipe and being provided with a plurality of radially extending lugs 29 adapted to slidably engage the inner walls of the fluid supply conduit to maintain the wash pipe centered therein and yet to permit flow of fluid therethrough.

Means are provided within the fluid supply conduit for slidably sealing wash pipe 21 therewith and to permit limited lateral movement of the wash pipe with respect to such conduit. Such means can comprise an annular flange 3% having an upturned collar extension 31. Collar 31 has a sliding fit with the wash pipe and has, received in an internal peripheral groove therearound, packing 32, and around its external circumference a resilient packing 33, such as rubber, adapted to be compressed and to permit limited radial movement of collar 31 and flange with respect to the fluid supply conduit. An annular ring 30a can be provided between flange 3t) and packing 33 to prevent the latters extrusion out of its position above the flange.

Anvil 12 is adapted to be attached by means of threads 34 to a bit 35.

The connection between the hammer and anvil is by inter-engaging slide and guide parts providing for limited longitudinal movement of the hammer and anvil with respect to each other. This connection can be accomplished by forming the end of the anvil most removed from bit 35 with a decreased diameter portion 56 adapted to be slidably telescoped in the hammer so that the latter is free to reciprocate with respect to the anvil. An annular shoulder 37 is formed on the anvil by reduced diameter portion 36 and this constitutes the percussive or impact face of the anvil. Hammer It) has an impact face 37a. It will be seen that this annular shoulder 37 will receive percussive blows from the hammer and transmit the energy therefrom through the anvil to hit To prevent relative rotation between the hammer and anvil, the connection therebetween can include a plurality of grooves or recesses 38 in impact section 13d cooperating with keys 39 carried by the reduced diameter portion of the anvil.

In. accordance with one aspect of this invention, stop means are provided as a part of the connection between the hammer and the anvil such that the freely extendable length of such connection is less than the distance the hammer may travel with respect to the fluid supply conduit. With such construction, after the stop means has stopped the sliding movement between the anvil and the hammer, the continued upward movement of the hammer will pull or hop the bit off the bottom of the bore hole and thereby permit it to be indexed. The stop means can be provided by a shoulder 40, formed byv counterboring the upper end of impact section 13d, engageable with split ring 41 seated in a recess in the reduced diameter portion of the anvil and held in place by garter springs 42. The distance between split ring 41 and shoulder 40 is adjusted to be less than the length of, grooves 38 so that keys 39 will be maintained in engagement with-their corresponding grooves when the tool is being lowered in the well. Moreover, this distance can also be adjusted tobe such that, split ring, 41 will abut shoulder 4-0 while the. hammer is still moving toward the fluid supply conduit so that the, upward momentum ofthe hammer will pull or hop the bit from the bottom of the bore hole. In this manner, the hammer is permitted to have limited longitudinal reciprocation with respect to the anvil and to hop the bit from the bottom thereby facilitating indexing. Thus torque applied to the hammer via the fluid supply conduit will be transmitted to the anvil to index 35 in the hole each time it is hopped off bottom. This mode of operation is optional and is useful mainly in those cases in which the nature of the formation and bit are such as to render indexing otherwise diflicult or impossible.

Keys 19 and 39 may, if desired in any case, be replaced or augmented by suitable torque transmitting means for reducing the frictional resistance to relative longitudinal movement between the parts which they connect.

To further clarify the disclosure at this point, the fluid flow will be traced through the apparatus as thus far described. Fluid passing from drill string 17 will flow through supply conduit 11 past lugs 29 and into wash pipe 21 via slots 21a. Flow externally of the wash pipe below these slots will be prevented by flange 30 and its attendant sealing parts. After fluid flows through passageway 21b in the wash pipe, it continues via passageways 15a, 13s, 137, 13g and 1311 to be discharged from the hammer. Such discharge can be via slots 12a and passageway 36a in the anvil to the bit from which it is discharged in the normal fashion. Thus it will be seen that there is an interconnecting fluid passageway between the fluid supply conduit and the hammer and, if desired, through the anvil.

In accordance with one aspect of this invention, first and second single acting fluid motors are operatively connected between the hammer and anvil and between the hammer and fluid supply conduit, respectively, to reciprocate the hammer and are adapted to be actuated by a unidirectional flow of fluid through the tool to alternately move the hammer in opposite directions and thereby cause it to have a power impact stroke towards the anvil and a power return stroke from the anvil. In general, these fluid motors include relatively movable parts on the conduit and hammer and on the hammer and anvil and can comprise valve means for limiting flow through the anvil and through the hammer, respectively, and adapted to become seated and unseated during certain portions of the movement of the hammer in such a manner that the fluid passing from the fluid supply conduit will not only lift the hammer to cause its telescopic connection with the anvil to be extended while retracting the telescopic connection thereof with the conduit, but also to apply fluid pressure to the hammer to stop its upward movement, if desired, and to drive it during a substantial portion of its power stroke. In this manner there is provided single acting fluid motor means for the hammer which gives it a double acting effect responsive to power exerted by a unidirectional flow of fluid.

The first fluid motor means is illustrated as comprising a valve-element-supporting,spider-type sleeve 50 having a running fit over the upper end of the reduced diameter portion 36 of the anvil and spaced from the end thereof by a removable spacer washer 51. This spacer washer can be replaced by other washers of different thicknesses to adjust the spacing of seating and valve elements described below. A fluid passage 52 is provided through spacer. 51 and sleeve 50 so that fluid may flow in limited quantity between sleeve 50 and portion 36 into such passage and between the sleeve and seating element 53, illustrated here as a ball. This fluid permits element 53 to be freely rotatable in its seat in the sleeve so as to wear evenly. To aid in this rotation, the radius of the depression in the sleeve for receiving the ball is slightly longer than that of the ball. This difference in radius has been somewhat exaggerated in the drawings to more clearly show the same. The ball is maintained in position on sleeve 50 by gravity and by fluid flowing therepast. Thus, in effect, seating valve element 53 is carried by the anvil above the fluid discharge from the hammer.

Cooperating with seating element 53 is a reciprocal valve element 54 preferably in the form of a piston having a sliding fit with wall 55 of the hammer and having a fluid passage 54a therethrough across which the seating element seats. Piston 54 has a sliding seal with Wall 55 by a seal 56. Annular inwardly extending wall portion 57 of valve element 54 presents a seat adapted to engage seating element 53 and to be closed thereby to prevent flow of fluid through the anvil or through the discharge from the hammer. Valve element 54 is biased away from the anvil by spring 58 acting through bail 59 and having its other end joined to the hammer through link 60 and cross-support member 61. It is noted that the upwardly biasing effect of spring 58 will be limited by a stop means comprising a shoulder 62 formed by the lower end of sub 13b and adapted to abut the upper end of the valve member.

It will be seen that when a higher pressure exists in passage 54a than in 13g, valve element 54 will be urged against seating element 53 and will remain in such position during a portion of the return stroke of the hammer. To unseat the valve member, stop means are provided as part of the valve means to urge the valve member out of contact with the seating element after the hammer has traveled a finite distance in its return stroke. Such means can comprise a shoulder 63 carried by the hammer and adapted to abut against a shoulder 64 on the valve member. The distance between these shoulders determines the distance through which the hammer will travel under the impetus of the driving fluid.

It is an important feature of this invention that a differential area be provided in the hammer as a part of the valve means to face away fromthe fluid supply conduit so that fluid can act thereagainst to urge the hammer towards the conduit. To do this, the cross-sectional area in the passage through the hammer at the engagement of valve element 54 with surface 55 is made larger than the cross-sectional area contained within packing 32 around wash pipe 21 or, in other words, larger than the effective outside area of the portion of the hammer telescoping within the fluid supply conduit. With this construction and when valve element 54 is seated against element 53, there will be a differential pressure area acted upon by the fluid from the fluid supply conduit to move the hammer to thereby extend its telescopic connection with the anvil. At the same time, the telescopic connec tion with the fluid supply conduit will be contracted.

It is believed apparent that during the return stroke of the hammer and at the instant shoulder 63 abuts shoulder 64 to unseat piston 54, the annular area equal to the cross-sectional area within bore 55 minus the cross-sectional area within the seat between piston 54 and ball 53 will be in effect subtracted from the diflerential area mentioned above. At such instant, the effective differential area becomes the cross-sectional area with the seat between piston 54 and ball 53 minus the crosssectional area within packing 32. In most instances during operation of the tool, the upward momentum of the hammer when shoulders 63 and 64 come into abutment will be great enough to pull piston 54 off its seat on ball 53 even though the area within the piston-ball seat is smaller than that within seal 32 and thus the opera tion of the tool can proceed. However, instances may occur when the hammer momentum is not great enough to unseat piston 54 and this is particularly apt to be true when the fluid first fed into the tool to start the hammer to reciprocate does not have suflicient rate of flow to rapidly lift the hammer so that it gains the required momentum. To positively assure that the hammer will always unseat piston 54, it is preferable that the area within the piston-ball seat be made sufficiently larger than the area within seal 32 that the hammer is positively 7 lifted upwardly during unseating of piston 54 even when the upward momentum of the hammer is essentially nil.

Since the apparatus thus far described is capable of operation independently of the remainder of the apparatus to produce limited results, its operation will be discussed before proceeding with the remainder of the apparatus.

eferring to the lower portion of Pig. 1 as well as to Figs. 2, 3 and 7A through 71), when a percussion drilling apparatus employing the impact tool of this invention is lowered into a bore hole, the anvil 12 will, by force of gravity, be extended from the hammer ltl until split ring 41 rests on shoulder 4-0 in the position shown in Fig. 1, it being understood that in the Fig. 1 position, the bit 35 is barely touching the bottom of the bore hole and that the apparatus is in a position as if suspended freely in mid-air. In this position, valve element 54 will be positioned by spring 58 with its upper end abutting shoulder 62 thereby maintaining it unseated from seating element 53 and permitting flow of fluid from the fluid supply conduit, through the passages in the hammer and thence through passage 54a in valve element 54 and out around seating element 53 to continue flow downwardly into slots 12a and thence to the bit. As the tool is lowered further into the hole with the bit resting on the bottom thereof, the telescopic connection between the harnmer and the anvil will be contracted until the lower end of the hammer closely approaches or rests on the striking face of the anvil. At such position, valve element 54 will be very closely spaced with respect to seating element 53. This smallspacing will cause a pressure differential to exist between the interior of element 54 and the exterior thereof which will force the element into seated position on element 53 as shown in Fig. 2. Immediately, when this occurs, flow of fluid through the anvil is limited or stopped and the pressure thereof seeks to force the anvil 12 out of the hammer 10. Since the bit is resting on the bottom of the hole, this will not be possible and, as a result, the pressure will act upwardly against the difl erential pressure area of the hammer existing between that of the outside diameter of element S land the outside diameter of wash pipe 21 to force the hammer away from the anvil thereby extending the telescopic connection therebetween. As the hammer progresses away from the anvil, valve element 54 will be maintained seated against element 53 by the fluid pressure differential thereacross until shoulder 64 is struck by shoulder 63 of the hammer to unseat valve element thereby permitting fluid to again flow downwardly throu h the hammer and anvil and out to the bit as shown in Fig. 3. Since the hammer has been given an upward momentum by the reaction of the fluid thereagainst, it will continue upwardly until its movement is halted by force of gravity or other means after which the hammer will enter its power stroke to descend and impinge on shoulder 37 of the anvil to deliver percussive energy to the bit.

After the Fig. 3 position wherein element 54 has been unseated, spring will urge it away such that the upper portion of the valve element is abutted against shoulder 62. As the hammer descends, valve element 54 will approach more and more closely to seating element 53 and, at the time the hammer strikes the anvil, there will be a short distance between the valve elements which constitutes an annular flow area across the seat. Since this annular flow area is restricted, there will be a pressure differential thereacross which will act to urge element 54- against element 53. In addition, the downward movement of the hammer, carrying with it valve element 5d, will give to the latter a downward momentum which will continue after the hammer has impinged on the anvil. Such downward momentum will carry valve element 54 until it seats against element Upon seating, the above described cycle will be repeated.

It is important to note that when valve element 54 is in its Fig. 7C position, a clearance 65 is maintained with shoulder 62. This permits the hammer to strike the anvil before element 54 contacts element 53 so that percussive energy is delivered to the anvil and not to the valve elements.

The second fluid motor provided in accordance with one aspect of this invention is arranged to be actuated alternately with the first fluid motor driving the hammer upwardly and to employ the force of the fluid flowing downwardly through the fluid supply conduit to drive the hammer downwardly during a portion of the hammers power stroke. in addition, this motor is constructed to permit overtravel of the hammer in the hammers return stroke and to employ the downwardly moving column of fluid through the fluid supply conduit to stop upward iovement of the hammer without any metallic shock derived from impingement of the hammer with the supply conduit.

Such a second fluid motor can comprise a valve means adapted to limit or stop fluid flow through the hammer so that the downwardly moving column of fluid will be impressed on the hammer to accelerate its power stroke. Referring particularly to Figs. 7A, 8 and 9, wash pipe 21 on the hammer is surmounted by sleeve 28 having a spherical depression therein adapted to receive a ball seating element so that this seating element is carried by the hammer and reciprocates therewith. The construction of this ball seating element and its carrier sleeve is substantially the same as described for valve element 53 and. its carrier. Reciprocally received in the fluid supply conduit in such a manner as to permit overtravel of the hammer is a valve element in the form of a piston 71 having. a fluid passage 71a and an inwardly extending portion 72 adapted to seat with seating element 70. In this respect, piston 71 is similar in construction and operation to valve element 54. A suitable packing ring 73 can be received around the piston to seal it from the wall and to prevent erosion thereof. Superposed above the piston and adapted to abut therewith is a sleeve 74 having equalizing fluid passage 7411 through its well and connected to piston 71 by spring 76 mounted on cross bars 77 and '78 in such a manner that piston 71 is biased toward sleeve 74. Stop means for sleeve 74 is provided as part of the valve means and can comprise an outturned shoulder 79 adapted to abut against a shoulder 80 on the supply conduit and thereby limit the sleeves downward movement but permit its free upward movement. Piston 71 is likewise provided with stop means to limit its downward travel and to unseat it after the hammer has traveled through a portion of its power stroke. This means can comprise shoulder 81 adapted to abut against shoulder 82 around the fluid supply conduit.

With piston 71 abutting sleeve '7 4 shown in Fig. 7A, it will be noted that the distance between shoulders 79 and 81b is less than the distance between, shoulders 31 and 32 so that movement of the hammer during its power stroke will first cause the sleeve to stop and then, after the hammer has moved an additional distance, to cause piston 71 to unseat from seating element 79. By such provision it will be noted that since a pressure dififerential exists across piston 71, it will continue following the hammer during its power stroke after sleeve 74 has been stopped and until it becomes unseated, which will result in separation of piston 71 from sleeve 7 so that when the piston becomes unseated, spring 76 can act to pull piston '71 away from its seat thereby permitting fluid flow through the tool.

From the foregoing description, it will be seen that the operation of this fluid motor for powering the piston during its power stroke by means of a unidirectional flow of fluid is such that the pressure of the fluid and its downward inertia will be exerted across the valve means provided by piston 71 to not only stop upward movement of the hammer but to greatly accelerate the piston during its power stroke. Thus, after the piston has been raised to contract its telescopic connection with the fluid supply conduit, piston 71 will be seated .on seating element 70 which will limit or stop the flow of fluid through the piston. Since the fluid is flowing downwardly, it will have sizeable momentum applicable across piston 71 to stop upward travel of the hammer. However, due to the slight compressibility of the fluid, which ordinarily will be drilling mud, and due to the breathing of the drill string, the hammer will not be stopped instantaneously but will continue traveling upwardly a short distance. As a result, piston 71 and sleeve 74 will be moved upwardly with the piston to remove shoulder 79 from shoulder 80. When the upward momentum of the hammer has been overcome, the full fluid pressure of the downwardly moving fluid, as well as the energy stored therein by stopping the upward movement of the hammer, will be exerted on the hammer across piston 71 to greatly accelerate its downward movement. During such movement, sleeve 74 and piston 71 will likewise move downwardly since a pressure differential exists across piston 71 to maintain it in seated position against seating element 70. After the hammer has moved downwardly a finite distance, shoulder 79 will abut shoulder 80 and stop further downward movement of the sleeve. However, piston 71 will continue its downward movement until it strikes shoulder 82 since the pressure differential urging it into seated position with the seating element 70 is greater than the opposing unseating force of spring 76. After this happens, full downward flow of fluid through the hammer will be effected. With the resultant loss of pressure differential across the piston, spring 76 will move it away from its seat to abut with sleeve 74.

With the arrangement of sleeve 74, spring 76 and piston 71 as described above, the downward travel of the hammer under the impetus of the unidirectional fluid will be equal to the distance of upward overtravel of the hammer plus the distance between shoulders 81 and 82 with piston 71 abutting sleeve 74 and with shoulders 79 and 80 in abutment. Under those conditions where the application of fluid pressure to the hammer to accelerate it during its power stroke can be over a distance equal to the overtravel of thehammer, it is contemplated that sleeve 74 and spring 76 can be omitted from the structure, leaving piston 71 freely slidable in the supply conduit. In such construction, the piston will move away from shoulder 82 a distance equal to the overtravel of the hammer and this distance will likewise be that during which the hammer is accelerated downwardly by fluid pressure. The piston will move only when seated on seating element 70. This type of construction willoften be suited for use with relatively elastic fluids, with a heavy hammer, with a long column of fluid or with a gas cut drilling mud.

From the foregoing, it will be apparent that the positioning of various elements, when constructed in accordance with the embodiment shown in the drawings, can be restated in geometric terms as follows:

1. To assure that clearance 65 will exist, the vertical distance between the part of piston 54 abutting with shoulder 62 and the anvil face 37, with piston 54 seated on ball 53, be sufficiently less than the vertical distance between shoulder 62 and the anvil striking face of the hammer to provide the desired clearance.

2. When it is desired that pistons 54 and 71 not be in seated position simultaneously during the return stroke of the hammer, the vertical distance between the seat at the lower end of piston 71 and the corresponding seat on ball 70, with the hammer resting on the anvil and with shoulders 79 and 80 in abutment, with piston 71 abutting sleeve 74 and with piston 54 seated on ball 53, must be greater than the vertical distance between shoulders63 and 64.

3. When it is desired that the two pistons not be in seated position simultaneously during the power stroke of the hammer, the spacing between the supply conduit 11 and anvil 12 is adjusted so that the vertical -10 distance between shoulder 82 and face 37 of the anvil is greater than the vertical distance between shoulder 81 and the anvil striking face 37a of the hammer when piston 71 is seated on ball 70; this assumes, of course, that clearance 65 has also been provided.

Obviously, prevention of simultaneous seating of pistons 54 and 71 and the provision of clearance 65 is particularly important when substantially incompressible liquid is being employed as a power fluid. The reason for this is that if the two pistons were seated at the same time, fluid lock of the tool would occur and the hammer could not be moved in its cycle by the liquid; and if clearance 65 is not provided, the hammer would deliver its energy to piston 54 instead of to the anvil and even if this were avoided, premature seating of piston 54 would rob the hammer of its energy available for delivery to the anvil since premature seating of piston 54 permits the power fluid to urge the hammer to begin its return stroke before it has struck the anvil. Of course, when an elastic power fluid is employed, the respective times of seating of the pistons are not as important due to the elasticity of such fluid.

Referring to Fig. 13, an alternative form of seating element is illustrated which is adapted to be substituted for either or both of elements 53 and 7t). It comprises a tapered seat element 66 threaded to the spider sleeve 28 and seating in the corresponding valve elements.

It is believed that the over-all operation of the tool of this invention will be apparent from the foregoing. However, to insure adequate disclosure, a brief description of its operation will be given referring particularly to Figs. 1, 4, 5 and 6.

As the tool is lowered towards the surface to receive the percussive blows, e. g. into a bore hole, the hammer will be suspended from the fluid supply conduit and the anvil from the hammer as shown in Fig. 1. While being lowered in the bore hole, the upper and lower valve means will be open permitting fluid flow through the tool. Continued lowering of the tool after bit 35 rests on the bottom of the bore hole will cause the hammer to telescope with the anvil until the lower end thereof rests on the impact face of the anvil.

As described above with respect to Figs. 1 and 2, this causes valve element 54 to seat and the hammer 10 to move upwardly as in Fig. 4. In so doing, seating element 70 will move closer to piston 71 and will be seated thereon after shoulder 63 has unseated valve element 54 from its seat. Since the hammer 10 still has some upward momentum after piston 71 and seating element 70 have mated, there will be overtravel of the piston to a position similar to that of Fig. 6. This overtravel lifts sleeve 74 from its abutment with shoulder until the force of the fluid thus applied to the hammer arrests its upward movement. At such time, the fluid force accelerates the hammers downward movement and sleeve 74 will again abut shoulder 80. Piston 71 continues its downward travel with the hammer until it strikes shoulder 82 and hence becomes unseated.

In the meantime and immediately after valve element 54 has become unseated, spring 58 moves the element into abutment with shoulder 62, thereby permitting the hammer to strike the anvil before element 54 is reseated on element 53. Fig. 5 shows the tool just after the hammer has delivered its blow to the anvil and after element 54 has been seated. In this view, spring 76 is starting to return piston 71 to its position abutting sleeve 74 to permit the hammer to travel through its full return stroke.

In the Fig. 6 position, it will be noted that split ring 41 is in contact with shoulder 40 and that the subsequent upward travel of the hammer has hopped the bit oif the bottom of the bore hole.

The length of the telescoping connection between the fluid supply conduit and the hammer can be made, and preferably is made, longer than the distance through which the anvil must be telescoped to seat element 53 11 with element 54. With this construction, the lower fluid motor can be operated without operation of the upper fluid motor by merely suspending the supply conduit sufflciently above the hammer so that element 70 will not seat with element 71. When this is done, the hammer is moved during its power stroke by gravity and returned by fluid pressure. It should be noted that as the fluid supply conduit is lowered toward the anvil the distance which the hammer must travel in order to seat seating element 7% with piston '71 will become less and, therefore, the stroke of the hammer may be regulated from the surface of the bore hole by merely regulating the elevational position of the fluid supply conduit with respect to the anvil. With the same power input to the tool, it is apparent that the shortening of the stroke of the hammer will increase the frequency of its movement.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.

it will be understood that certain features and subcom binations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

This application is a continuation-in-part of my application Serial No. 238,556 flled July 25, 1951, now abandoned.

The invention having been described, what is claimed is:

1. A fluid actuated impact tool which comprises, in combination, a fluid supply conduit, an anvil, a hammer telescopically engaging said conduit and said anvil for reciprocation therebetween and for impact against said anvil, said hammer having a fluid passageway connecting with that in said conduit, two alternately operable single acting fluid motors, one connected between said conduit and hammer to drive the latter toward said anvil for impact therewith and the other connected between said hamrner and anvil to drive said hammer toward said conduit, said motors being disposed to be actuated by a unidirectional flow of fluid passing through said conduit and through said passageway in said hammer, respectively, to reciprocate said hammer and means for rendering said motors alternately operable and inoperable to drive said hammer.

2. An impact tool which comprises, in combination, a fluid supply conduit, an anvil, and a hammer disposed between said conduit and anvil, said hammer and conduit having an interconnecting flow passageway therein, said hammer and conduit having inter-engaging slide and guide parts thereon providing for limited longitudinal movement of said conduit and hammer relative to each other, said hammer and anvil having inter-engaging slide and guide parts thereon providing for limited longitudinal movement of said anvil and hammer relative to each other, a first single acting fluid motor comprising relatively movable parts on said conduit and hammer respectively and disposed to urge said conduit and hammer away from each other during at least a portion of the hammers power stroke and to be actuated during such portion of such power stroke by fluid flowing in said passsgeway, a second single acting fluid motor comprising relatively movable parts on said hammer and anvil respectively and disposed to urge said hammer and anvil away from each other during at least a portion of the hammers return stroke and to be actuated during such portion of such return stroke by fluid flowing in said passageway and means rendering said first and second motors alternately operable and inoperable to move said hammer between said conduit and anvil.

3. An impact tool comprising a fluid supply conduit,

a hammer, and an anvil, said hammer being disposed between said conduit and" said anvil and having a flow passageway therein communicating with the interior of said conduit, said conduit and hammer having interengaging slide and guide parts thereon providing for limited longitudinal movement of said conduit and hat mer relative to each other, said hammer and anvil having interengaging slide and guide parts thereon providing for limited longitudinal movement of said hammer and anvil relative to each other, a first single acting fluid motor comprisng rciatively movable parts on said hammer and anvil, respectively, and disposed to urge said hammer and anvil away from each other on the hammers return stroke and to be actuated 'on such return stroke by fluid flowing through said hammer toward said anvil, a second single acting fluid motor comprising relatively movable parts on said conduit and said hammer, respectively, and disposed to urge said conduit and hammer away from each other on the hammers power stroke and to be actuated on such power stroke by a fluid flowing through said conduit toward said hammer and means for rendering said first motor inoperable to move the hammer while the second motor is in its power stroke and for rendering the second motor inoperable to move the hammer while the first motor is in its power stroke.

4. The apparatus of claim 3 in combination with mutually engaging stop means carried by said hammer and anvil to limit the longitudinal movement with respect to each other to be less than the permissible longitudinal movement between the conduit and hammer.

5. The apparatus of claim 3 wherein one of said relatively movable parts is a valve member and the other a seating member, the valve and seating member being arranged to restrict flow through the passageway in one of said hammer and conduit, said rendering means unseating said valve member and seating member in rendering inoperable the fluid motor comprising such mem bers.

6. A fluid actuated impact tool which comprises, in combination, a fluid supply conduit, an anvil, a reciprocal hammer, said conduit, anvil and hammer having connections with each other such that the anvil can move longitudinally relative to the conduit and the hammer can reciprocate relative to the conduit to deliver blows to the anvil, said hammer having a fluid passageway therethrough connected with that in said conduit, two fluid motors operatively connected to said hammer and alternately operable to move the hammer in opposite directions respectively and powered by a unidirectional flow of fluid through the tool, one of said fluid motors comprising a valve means adapted to seat and to limit flow from the conduit through the hammer so pres. .ne from said conduit drives the hammer in its power stroke and means for rendering the other of said motors inoperable to move the hammer while said valve means is seated and for unseating the valve means when said other motor is operable to move the hammer.

7. A fluid actuated impact tool which comprises, in combination, a' fluid supply conduit, an anvil, Cipro-- cal hammer, said conduit, anvil and hammer having connections with each other such that the anvil can move longitudinally relative to the conduit and the hammer can reciprocate relative to the conduit to deliver blows to the anvil, said hammer and anvil having a fluid pas sag'eway therethrough connected with that in said conduit, and two fluid motors comprising a first and a second valve means adapted to close and limit unidirectional flow of fluidthrough said anvil and said hammer respectively, the total area of surfaces on said hammer upstream of said second valve means disposed for pressure fluid from said conduit to act against to urge the hammer away from the anvil being greater than the total area of surfaces on the hammer disposed for pressure fluid from said con duit to act against to urge the hammer toward the anvil, means carried by the hammer for opening the first valve predetermined movement of the hammer toward the conduit and for opening the second valve means upon movement of the hammer away from the conduit.

8. A fluid actuated impact tool which comprises, in combination, a fluid supply conduit, an anvil, a reciprocal hammer between said anvil and conduit and having telescopic connections with each, said conduit and hammer having interconnecting fluid passageways therein with a discharge from said hammer, first valve means comprising a first member reciprocally received in said hammer upstream of said discharge to seat with a secondmember carried by said anvil and thereby limit flow through said discharge when the hammers telescopic connection with said anvil is contracted, means .for unseating said first member from said second member when said connection is extended, the passageway in which said first member is received in said hammer havinga greater cross-sectional area than the portion of the hammer telescoping with the conduit, second valve means comprising a first element reciprocally received in said passageway in said conduit to seat with a second element carried by the hammer and limit flow through the hammer, when its telescopic connection with the conduit is contracted and means for unseating said first element from said second element when said last connection is extended.

9. The tool of claim 8 wherein stop means comprising mutually engaging parts carried by said hammer and anvil, respectively, are provided to limit the freely extendable length of said telescopic connection between the hammer and anvil to les's than that of the telescopic connection between said hammer and conduit.

10. A fluid actuated impact tool which comprises, in combination, a fluid supply conduit, an anvil, a reciprocal hammer telescopically connected with said anvil for limited sliding movement with respect thereto and having a portion slidably telescoping within said conduit, said conduit, anvil and'hammer having interconnecting fluid passageways therein with an enlarged portion of the passageway in said hammer being of greater cross-sectional area than the cross-sectional area of said hammer portion telescoping within said conduit, first valve means for limiting flow through the anvil comprising two elements, the first carried by the anvil and the second being reciprocally received in said enlarged portion of'the passagewayin said hammer and seating with said first element when the hammer-anvil telescopic connection is contracted, means for unseating the valve elements after the hammer has moved a finite distance to extend last said connection, second valve means comprising an element carried by the hammer and an element slidably received in said fluid supply conduit to seat withthe hammer-carried element and limit flow through said hammer when the hammer-conduit connection has been contracted and to be unseated after last said connection has been extended a finite distance and means for limiting the movement of the slidable element in said conduit.

11. The tool of claim 10 wherein stop means comprising mutually engaging parts carried by said hammer and anvil, respectively, are provided to limit the freely eX- tendable length of said telescopic connection between the hammer and anvil to less than that of the telescopic connection between said hammer and conduit.

12. A fluid actuated percussion drilling tool which comprises, in combination, a. fluid supply conduit, an anvil, a hammer telescopingly connected with said anvil and having a portion telescoping within said conduit for reciprocation between said anvil and conduit, said conduit, hammer and anvil having interconnecting fluid passageways therethrough with an enlarged portion within said hammer of greater cross-sectional area than the and anvil, respectively, 25

14 portion of the hammer telescoping within said conduit, first valve means comprising a piston with a fluid passage therethrough slidingly received in said enlarged portion of said passageway, a seating element carried by said anvil adapted to seat across said piston passage, means carried by said hammer to unseat said piston after said hammer .has moved a substantial distance away from the anvil, means'biasing said piston away from the seating element and second valve means tively movable parts onsaid hammer and conduit, respectively, and disposed to urge said hammer and conduit away from each other when seated under the impetus of fluid flowing through said conduit towards said hammer.

13, The tool of claim 12 in combination with stop means carried by said piston and hammer for mutual engagement responsive to said biasing means, at a point sufliciently removed from said anvil that when said hammer-anvil telescopic connection is fully contracted, a restricted flow passage exists between said piston and said seating element.

14. The tool of claim 13 wherein stop means comprising mutually engaging parts carried by said hammer are provided to limit the freely extendable length of said telescopic connection between the hammer and anvil to less than that of the telescopic connection between said hammer and conduit.

15. A fluid actuated impact tool which comprises, in combination, a fluid supply conduit, an anvil, a hammer telescopically connected with said anvil and having a portion telescoping into said conduit, said hammer and conduit having interconnecting fluid passageways with a discharge from said hammer, first valve means comprising relatively movable parts on said anvil and hammer and disposed to seat to limit fluid flow from said hammer to said discharge to thereby urge said hammer to extend its connection with said anvil by a fluid flowing into said hammer towards said discharge, means for unseating said parts upon predetermined extension of the last mentioned connection, and second valve means to cause said hammer to be fluid driven during its power stroke towards said anvil comprising a seating element carried by said hammer, a valve element slidably carried by said fluid conduit in the passageway therein and adapted to seat with said seating element to limit flow through said hammer, means biasing the valve element away from the seating element, the cross-sectional area eifective area of the valve element upon which pressure acts to urge it towards seated position, the total area of surfaces on said hammer upstream of said first valve means disposed for pressure fluid 'frornsaid conduit to act against to urge the hammer away from the anvil being greater than the total area of surfaces on the hammer disposed for pressure fluid from said conduit to act against to urge the hammer towards the anvil.

16. The tool of claim 15 in combination with stop means carried by the conduit and hammer for mutual tance to extend its connection 17. The tool of claim 16 wherein the slidable valve element is connected by the biasing means to a slidable sleeve received in said passageway in said conduit, stop means carried 'by the conduit and sleeve for mutual engagement to limit the sleeves movement towards the end of the conduit connected to the hammer but permitting movement in an opposite direction to provide for overtravel of the hammer, said stop means for the sleeve being engaged at a point more removed from said end of the conduit than the point at which the stop means for the valve element are adapted to become engaged.

18. As a subcombination, a fiuid supply conduit, a hammer, and an anvil, said hammer being disposed between said conduit and anvil and having a flow passageway comprising relatherein communicating with the interior of said conduit, and said conduit and hammer having interengaging slide and guide parts thereon providing for limited longitudinal movement of said hammer and conduit relative to each other, said hammer and anvil having interengaging slide and guide parts thereon providing for limited longitudinal movement of said hammer and anvil relative to each other, and a single acting fluid motor comprising relatively movable parts on said hammer and anvil, respectively, and disposed to urge said hammer and anvil away from each other during at least a portion of the hammers return stroke and to be actuated during such portion of the return stroke by fluid flowing through said hammer toward said anvil, and means responsive to movement of the hammer for rendering said motor alternately operable and inoperable.

19. As a subcombination, a fluid supply conduit, an anvil, a reciprocal hammer having a sliding telescopic connection with the anvil and a portion slidably telescoping within the conduit, said conduit and hammer having an interconnecting fluid passageway with a discharge from the hammer, valve means comprising a first element carried by the anvil and a second element slidably received in the hammer to seat on the first element upstream or": said discharge to limit flow from said hammer, the effective pressure area of surfaces on the hammer upstream of said valve means and disposed for fluid pressure to act against to urge the hammer away from the anvil being greater than the cross-sectional area of said hammer portion telescoping within said conduit, said valve means including stop means for unseating said valve elements when said hammer has been moved to extend its telescopic connection with said anvil.

20. The subcombination of claim 19 wherein said second valve element comprises a piston reciprocal in a bore in the hammer and having a fluid passage therethrough across which said first element seats to limit flow through said discharge, the fluid passage being sufliciently restricted relative to said bore to permit a pressure differential across the piston to cause it to remain in seated position until said unseating means causes it to unseat.

21. The subcombination of claim 20 which includes means for biasing said piston away from said first valve element in such a manner that when the piston is unseated by said unseating means, it will be moved to a point more remote from said anvil.

22. The subcombination of claim 21 wherein said point is located such that the hammer-anvil connection is fully contracted before said piston is seated with said first valve element.

23. A fluid actuated impact tool which comprises, in combination, a fluid supply conduit, an anvil, a reciprocal hammer, said conduit, anvil and hammer having connections with each other such that the anvil can move longitudinally relative to the conduit and the hammer can reciprocate relative to the conduit to deliver blows to the anvil, a flow passageway through the tool, first valve means comprising a first valve member carried by the hammer and a second valve member carried by the anvil and cooperable with the first valve member to restrict flow from the tool upon the hammer moving through its power stroke to a perdetermined proximity of the anvil and during at least a portion of the return stroke of the hammer, second valve means upstream of the first valve means and comprising a first valve element carried by the conduit and a second valve element carried by the hammer and cooperable witi the first valve element to restrict flow from said conduit through said passageway upon the hammer moving through a predetermined portion of its return stroke and during at least a portion of the hammers power stroke, said hammer with the first valve means in flow restricting position and the second valve means open having an effective area against which fluid pressure of the conduit can act to urge the hammer in its return stroke which area is larger than any eflective area on the hammer disposed to urge the hammer in its power stroke under the influence of fluid from said conduit.

24. A fluid actuated impact tool which comprises, in combination, a fluid supply conduit, an anvil, a reciprocal hammer, said conduit, anvil and hammer having connections with each other such that the anvil can move longitudinally relative to the conduit and the hammer can reciprocate relative to the conduit to deliver blows to the anvil, said hammer having an effective endwise surface disposed for fluid pressure from the conduit to act thereagainst to urge the hammer in it return stroke, said endwise surface being of greater area than any effective opposing surface on the hammer which is exposed to said fluid pressure at the same time as said endwise surface is exposed during the hammers movement in its return stroke, a first fluid passageway connecting when open between said conduit and surface, a second fluid passageway in the anvil connecting between the exterior of the tool and said hammer surface, first and second valve means including valve parts respectively carried by the conduit and the hammer and by the, hammer and the anvil, said first and second valve means being arranged to open and close said first and second passageways respectively as the hammer moves in its power and return strokes so that fluid pressure is alternately applied to and exhausted from said hammer surface and, during the hammers power stroke, the first valve means restricts flow from the conduit and causes pressure in the conduit to be applied to the hammer to drive it in its power stroke, whereby relative longitudinal movement between the conduit and anvil varies the beating frequency of the hammer.

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